This can happen if there is an issue with the WordPress site and VideoSnack cannot connect or something is blocking it, like a security plugin disabling certain WordPress features.
If you have a security WordPress plugin, make sure that the Application Password feature is not disabled.
WordFence
If you have WordFence installed please go to WordFence-> Firewall, scroll to the Disable WordPress application password option and uncheck it. Save the settings and try to connect again.
Now the pop-up for connecting your Google account to your site will work.
All In One WP Security
Go to WP Security -> User Login -> Additional Settings
Make sure the Application Password is not disabled.